The causes boil down to the usual suspects: High cost of living, particularly for housing, combined with lackluster job creation outside of low-paying tourism or high-paying technology sectors.

“We’re an expensive place to live and do business,” said Kelly Cunningham, chief economist at National University’s Institute for Policy Research. “We’re still seeing an exodus of middle-wage workers (who) can’t find jobs or can’t afford to live here.”

Hasn’t San Diego always had such problems? Partly, yet they are getting bigger.

Local housing prices surpassed the national average in the 1970s, and the spread has grown ever since, says Cox, the SANDAG economist.

These high costs flow from political decisions that have been popular over time, ranging from zoning restrictions to fees for affordable housing and ballot-box growth limits.

Until recently, cities could power through their own restrictions using redevelopment agencies.

The results were mixed, but they were better than nothing in some cases. Now the state has outlawed redevelopment agencies in a tax grab.

“Home prices will continue to rise if it’s more difficult to build a house,” Cox said.

So the construction industry, a growth engine in a typical economic recovery, may not produce as many jobs in the future.

Other industries face a long list of obstacles of their own. Taxes are among the nation’s highest, and most enjoy popular support. A push for green energy has produced the mainland’s highest utility and fuel prices.

And during the last two housing booms cities rezoned industrial and office land for housing and retail, further boosting costs.

The exodus of skilled workers to Phoenix, Las Vegas and Texas cities reflects a stubborn drought in jobs for middle-wage workers in San Diego.

Hope for higher wages resides with the region’s considerable university and research nexus, Cox said, as valued-added activity of the knowledge-based economy creates demand for workers with skills in math and science.

Yet tech executives complain about the same costs as their colleagues in defense, manufacturing and construction. Once innovative products are developed in San Diego labs, they are generally produced somewhere else.

Government workers have enjoyed some of the biggest wage growth of any sector since the mid-1990s. Their gains have come at the expense of infrastructure investment that could improve both business conditions and quality of life for workers.

Reversing such big economic and demographic trends would require a change of heart for many of the same policymakers who’ve had a hand in creating them.

Meanwhile, voters wonder how their children will afford to live here.

Yet the policies and politicians behind such worries remain popular at the ballot box.

All those people leaving town are a symptom of economic woes, and not yet a cause. So far, that seems just fine with most San Diegans.